The present invention relates generally to a change-speed gearing assembly for motor vehicles, and more particularly to a lubrication arrangement in the change-speed gearing assembly.
As is illustrated in FIG. 4, a conventional change-speed gearing assembly comprises a casing 1 formed with an upright partition wall, a pair of bearings 3 and 5 carried on the upper and lower portions of the partition wall respectively for rotatably supporting thereon upper and lower shafts 6 and 7, and a bearing retainer 2 secured in a fluid-tight manner to the outside face of the partition wall to retain both the bearings 3 and 5 in place. The bearing retainer 2 is formed therein with upper and lower cavities R.sub.1 and R.sub.2, in which the outside portions of the bearings 3, 5 are exposed respectively, and is formed with a vertical groove P for communication between the upper and lower cavities R.sub.1 and R.sub.2. The upper shaft extends outwardly through an annular oil seal member 4 carried on the bearing retainer 2 coaxially with the upper bearing 3 and exposed at its inside face to the interior of the upper cavity R.sub.1. In operation of the change-speed gearing assembly, an amount of lubricating oil stored in the casing is picked up by rotation of gears mounted on the shafts 6, 7 and in mesh with each other. A portion of the picked up lubricating oil is fed into the upper cavity R.sub.1 through an axial hole in the partition wall to lubricate the oil seal member 4 and the upper bearing 3 and returns into the casing 1 across bearing 3. The remaining portion of the lubricating oil flows into the lower cavity R.sub.2 through the vertical groove P to lubricate the lower bearing 5 and returns into the casing across bearing 5.
In such a lubrication arrangement in the change-speed gearing assembly, the vertical groove P is positioned on a vertical line between the upper and lower shafts 6 and 7. For this reason, in the case that the quantity of lubricating oil fed into the upper annular cavity R.sub.1 becomes small during low speed rotation of the gears or a sealed bearing is utilized as the upper bearing 3 to store an amount of lubricating oil in the upper cavity, lubrication of the oil seal member will be insufficient because the vertical groove P permits therethrough a flow of lubricating oil into the lower cavity R.sub.2. This causes fatigue of the oil seal member 4 in a short period of time, resulting in leakage of the oil across the seal member.